Outlook Not Working? Fixes for New and Classic Outlook

Outlook freezing, crashing or refusing to open usually has one of a handful of causes, and Microsoft's own troubleshooting steps work through them in a sensible order. The fixes are different for new Outlook and classic Outlook, so the first job is knowing which you have. Here's how to tell, and what to do in each.

New Outlook or classic Outlook?

Look at the top of the window. If there's a File tab, you're using classic Outlook. If there isn't, it's almost certainly new Outlook for Windows. The fixes below are split that way.

New Outlook: force it closed and reopen

1. Right-click the Start button and choose Task Manager.
2. Select Microsoft Outlook, then End task.
3. Check Outlook has closed, then close Task Manager.
4. Open Outlook again as normal.

That clears most freezes. If new Outlook keeps hanging, uninstall it from the Start menu (expand its options and choose Uninstall), then reinstall it from the Microsoft Store. Microsoft notes new Outlook needs Windows 10 version 17763.0 or later.

Classic Outlook: work through these in order

Step	Why it helps
Check the status bar and wait a few minutes	Outlook may be busy with auto-archive or a large attachment
Install Office and Windows updates	They replace out-of-date files that cause problems
Start in safe mode	Shows whether an add-in is to blame
Create a new profile	Tests whether your profile is corrupted
Repair your data files	Fixes damaged mail files with the Inbox Repair Tool
Repair Office	Fixes damaged program files

Is it busy, not broken?

Microsoft points out that classic Outlook sometimes runs jobs in the background, such as auto-archive, sending or receiving a very large attachment, or mailbox tools. Check the status bar at the bottom of the window. If something's running, wait a couple of minutes before you force anything closed, because interrupting it can make things worse.

Start classic Outlook in safe mode

1. Press the Windows key and R together to open Run.
2. Type outlook.exe /safe and click OK.
3. If asked to choose a profile, accept the default.

If Outlook works in safe mode, an add-in is the likely culprit. Go to File, Options, Add-ins, choose COM Add-ins and select Go. Clear every tick to disable them, restart Outlook, then turn them back on one at a time until the problem returns. Microsoft's warning is worth repeating: clear the tick boxes, don't select Remove, or you could delete an add-in rather than just switching it off.

Try a new profile

Your Outlook profile holds your settings, and it can become corrupted. Create a new profile, then hold Shift while starting Outlook and choose the new profile from the list. If Outlook behaves with the new one, your old profile was the problem.

Repair data files and Office

Classic Outlook stores your mail, calendar and contacts in data files, which can occasionally get damaged. Microsoft's Inbox Repair Tool, scanpst.exe, scans and fixes them. If the program itself is damaged, repair Office from Windows settings: try the quick repair first, and the online repair if that doesn't work.

When it's only sending or receiving that fails

Sometimes Outlook opens fine but mail won't move. Look at the status bar for words like Disconnected or Working Offline, which mean Outlook can't reach your mail server. Check your internet, and if you've recently changed your email password, make sure Outlook has the new one, as an old saved password stops mail flowing without much warning. A full mailbox can also stop messages arriving, so clear out large old emails and empty Deleted Items if you're near your storage limit.

Using Outlook.com in a browser?

If the problem is with Outlook.com or Outlook on the web rather than the Windows app, Microsoft keeps a page of fixes and workarounds for recent issues. Check it first, because some problems are on Microsoft's side and simply need waiting out.

Before you start fixing

• Check your internet connection with any other website.
• Restart your computer, which clears a surprising number of problems.
• Note any error message word for word; it's the fastest route to the right fix.
• If it's a work computer, tell IT before reinstalling anything.

If Outlook started misbehaving straight after you opened a suspicious email or attachment, stop troubleshooting and read up on business email attacks, then talk to whoever looks after your IT, because that's a security question rather than a settings one. My office productivity hacks cover more ways to keep your tools running smoothly.

My verdict

For new Outlook, end the task and reopen, then reinstall from the Microsoft Store if it keeps failing. For classic Outlook, wait out background jobs, update, then use safe mode to rule out add-ins, a new profile to rule out corruption, and the repair tools last. Most problems are fixed by step three.

Frequently asked questions

Why is Outlook not working on my computer?

Common causes are a frozen app, a faulty add-in, missing updates, a corrupted profile or damaged data files. Microsoft's fixes start with closing Outlook in Task Manager and reopening it.

How do I start Outlook in safe mode?

Press Windows key + R, type outlook.exe /safe and click OK. This starts classic Outlook without add-ins.

How do I fix new Outlook freezing?

End Microsoft Outlook in Task Manager and reopen it. If it keeps freezing, uninstall it and reinstall from the Microsoft Store.

How do I repair Outlook data files?

Microsoft's Inbox Repair Tool, scanpst.exe, scans and repairs classic Outlook data files.

Should I remove Outlook add-ins to fix problems?

Disable them rather than remove them. Microsoft says to clear the tick boxes, not select Remove, then re-enable one at a time.